Presently, conventional weld wire is made from large cast ingots, e.g., 20 inches (50.8 cm) square by 90 inches (228.6 cm) long, which must be hot and cold rolled down to final size, e.g., 1/8 inch (0.32 cm) diameter wire. This is wasteful of manpower, energy and material. Also, certain desirable compositions for weld wire are difficult or impossible to process to wire by conventional ingot metallurgy. Furthermore, weld wires with low volume or low turnover rates can be wasteful of capital due to inventory costs.
Direct extrusion and consolidation of powder metallurgy (P/M) processed alloys would overcome the above difficulties. However, P/M extrusion techniques have not been adopted by the welding electrode industry. There appear to be only a few references applying P/M techniques to welding wire. And of these most deal with coating a conventionally wrought base wire by consolidating the alloy powder about the prefabricated wire. See for example Treatise on Powder Metallurgy Volume II by C. G. Goetzel, Interscience Publishers, Inc., New York 1950, page 568 and The Extrusion of Metals by C. E. Pearson, John Wiley & Sons Inc., New York 1944, page 201. The former reference refers to "an ingot iron base wire" and the latter reference briefly refers to "the preparation of special rods for arc welding" but does not give details.
An article that does present details is entitled "Extruded Powder Metal Welding Rods" by F. C. Kelly and F. E. Fisher, "The Iron Age" December 19, 1946, pages 68-72. 18-8 welding rods of moderate density (about 75%) were fabricated. These experimental rods are not believed to be able to withstand the rigors of modern, high speed, automated coating processes. Indeed, welding rods having densities below about 90% are not useful since they tend to break apart and decrease product yields below commercially acceptable levels.